CRF and Stress Modulation of Phasic Dopamine Release and Behavior

描述（由申请人提供）：与治疗药物成瘾有关的一个更令人生畏的问题是复发率高，据报道，高达90%的成瘾者都有复发率。复发往往是由于暴露于压力事件；因此强调了基础科学研究的必要性，以表征压力影响动机行为的神经回路。先前的研究表明，腹侧被盖区（VTA）的多巴胺细胞很好地调节了压力和动机之间的相互作用，但迄今为止还没有直接测试。因此，在K99/R00的“独立途径奖”提案中，研究计划的主要目标是评估压力相关肽，厌恶线索和压力刺激如何直接影响阶段性多巴胺释放，这是与促进动机行为直接相关的多巴胺释放模式。为了实现这一目标，快速扫描循环伏安法将被用于监测大鼠在执行评估动机的操作性任务时的阶段性多巴胺释放，并结合大脑区域特定的药理操作。在该奖项的指导阶段，候选人将研究压力释放神经肽促肾上腺皮质激素释放因子（CRF）如何在VTA中作用，以影响动机行为和伏隔核对自然（Aim 1）和药物（Aim 2a）强化物的奖励相关刺激的阶段性多巴胺释放。由于药物暴露诱导多巴胺系统内的突触变化，包括CRF如何与多巴胺神经元相互作用，候选人下一步将评估先前的药物摄入如何影响CRF对自然强化物动机行为的影响（Aim 2b）。有了压力相关神经肽如何影响阶段性多巴胺释放和行为的基础，在独立阶段的后续实验将直接研究压力（可逃避的和不可逃避的）和压力相关线索如何影响伏隔核的行为和阶段性多巴胺释放（Aim 3a）。新出现的证据表明，前额叶皮层和杏仁核中儿茶酚胺（多巴胺和去甲肾上腺素）的释放也参与调节对压力的反应，因此候选人还将讨论这些大脑区域中儿茶酚胺的阶段性释放如何受到压力和压力相关线索的影响（Aim 3b）。该研究结果不仅对成瘾研究具有重要意义，对压力、动机和阶段性儿茶酚胺释放之间的相互作用具有重要意义，而且为未来的实验奠定了基础。本项目设计的研究是候选人先前（细胞水平分析CRF调节多巴胺神经元放电率）和当前工作（检查动机行为期间的阶段性儿茶酚胺释放）的逻辑延伸和协同融合。候选人将在他的导师Paul Phillips博士的建议下熟练地进行药物自我给药研究，并与Jeansok Kim博士进行咨询，通过在压力操作期间结合伏安法记录来增加候选人的实验曲目。拟议的职业发展计划旨在为候选人提供实现其长期目标的最佳机会，即成为一名独立的终身研究员，从事神经科学研究，重点研究儿茶酚胺在行为中的作用。具体来说，候选人将努力实现这一长期目标，通过执行拟议的研究，参加华盛顿大学的各种科学研讨会，在科学会议上发表演讲，在研究生水平的课程上讲授药物滥用和成瘾，并参加课程以提高他的科学智力。候选人将获得职业发展建议，并在每月与主要导师Phillips博士和共同导师Charles Chavkin博士的联席会议上对其进展进行评估。菲利普斯博士率先使用长期植入的电极进行伏安法记录，这种电极可以存活数月，因此为进行这些实验提供了良好的环境。此外，华盛顿大学和药物成瘾研究中心的氛围有利于培养年轻科学家，最近的K99/R00获奖者已经过渡到独立的科学事业就是证明。

DESCRIPTION (provided by applicant): One of the more daunting problems associated with treating drug addiction is the high incidence of relapse, which has been reported to occur in up to 90% of addicted individuals. Relapse is often precipitated by exposure to stressful events; thus highlighting the need for basic science research to characterize the neural circuits by which stress affects motivated behavior. Previous studies suggest that the dopamine cells of the ventral tegmental area (VTA) are well situated to mediate the interaction between stress and motivation, but to date this has not been directly tested. Therefore, the primary goal of the research plan in this K99/R00 'Pathway to Independence Award' proposal is to assess how stress-related peptides, aversive cues, and stressful stimuli directly affect phasic dopamine release, which is the pattern of dopamine release directly associated with promoting motivated behavior. To address this goal, fast-scan cyclic voltammetry will be utilized to monitor phasic dopamine release in combination with brain-region specific pharmacological manipulations in rats performing operant tasks that assess motivation. During the mentored phase of the award, the candidate will examine how the stress-released neuropeptide corticotropin-releasing factor (CRF) acts in the VTA to affect motivated behavior and phasic dopamine release in the nucleus accumbens to reward-related stimuli for natural (Aim 1) and drug (Aim 2a) reinforcers. Because drug exposure induces synaptic changes within the dopamine system, including how CRF interacts with dopamine neurons, the candidate will next assess how prior drug intake influences CRF's effect on motivated behavior for natural reinforcers (Aim 2b). With this foundation of how a stress-related neuropeptide affects phasic dopamine release and behavior, subsequent experiments during the independent phase of the award will directly examine how stress (escapable and inescapable) and stress-associated cues affect behavior and phasic dopamine release in the nucleus accumbens (Aim 3a). Emerging evidence suggests that catecholamine (dopamine and norepinephrine) release in the prefrontal cortex and amygdala are also involved with mediating the response to stress, so the candidate will also address how phasic catecholamine release in these brain regions is affected by stress and stress-associated cues (Aim 3b). The findings from the proposed work will not only be of great importance to addiction research by yielding valuable findings on the interaction between stress, motivation, and phasic catecholamine release, but will also lay a foundation for future experimentation. The research designed in this project is a logical extension and synergistic amalgamation of the candidate's previous (cellular level analysis of CRF modulating dopamine neuron firing rate) and current work (examining phasic catecholamine release during motivated behavior). The candidate will become proficient in performing drug self-administration studies under the advising of his mentor Dr. Paul Phillips, and consulting with Dr. Jeansok Kim will add to the candidate's experimental repertoire by incorporating voltammetry recordings during stress manipulations. The proposed career development plan is designed to afford the candidate the best opportunity of achieving his long-term goal of becoming an independent tenure-track investigator conducting neuroscience research focused on examining the role of catecholamines during behavior. Specifically, the candidate will strive toward this long-term goal by performing the proposed research, attending various scientific seminars at the University of Washington, presenting at scientific conferences, giving lectures to graduate level classes about drug abuse and addiction, and taking classes to enhance his scientific intellect. The candidate will receive career development advising and will be evaluated on his progress in his monthly joint meetings with his primary mentor, Dr. Phillips and co-mentor, Dr. Charles Chavkin. Dr. Phillips pioneered voltammetry recordings using chronically implanted electrodes that remain viable for months, and as such provides an excellent environment to perform these experiments. Furthermore, the atmosphere at the University of Washington and through the Center for Drug Addiction Research is conducive for developing young scientists, as evidenced by the recent awardees of the K99/R00 whom have transitioned to independent scientific careers.